WordPress Amelia Plugin Stored XSS via Authentication Bypass

The Booking for Appointments and Events Calendar – Amelia plugin for WordPress is vulnerable to Stored Cross-Site Scripting via customer name fields in versions up to and including 2.2. This is due to an authentication bypass where the AddBookingCommand explicitly skips nonce verification (Command.php line 186), allowing unauthenticated users to submit booking data. While the plugin applies sanitize_text_field() to customer firstName and lastName fields (BookingApplicationService.php lines 302-308), this function only removes HTML tags and preserves special characters including double quotes. The vulnerability manifests in the administrative Calendar view where a FullCalendar eventContent callback interpolates customer names directly into JavaScript template literals (redesign/dist/index.js line 199) and renders them via innerHTML without proper HTML entity encoding. Because double quotes are preserved, an attacker can inject payloads like '" onmouseover="alert(document.cookie)"' to br

Casky was already ahead

This CVE exploits attack patterns that Casky's 323matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

The Booking for Appointments and Events Calendar – Amelia plugin for WordPress contains a critical stored cross-site scripting (XSS) vulnerability affecting versions up to 2.2. An authentication bypass in the AddBookingCommand class explicitly skips nonce verification, allowing unauthenticated attackers to submit malicious booking data. While the plugin attempts to sanitize customer name fields using sanitize_text_field(), this function is insufficient to prevent XSS attacks when combined with improper output encoding later in the application. Any WordPress site running this plugin becomes vulnerable to attackers injecting persistent malicious scripts through booking forms, which execute in the browsers of administrators and other users who view booking records. This affects organizations relying on Amelia for appointment scheduling and event management across the WordPress ecosystem.

Casky's 323 matching skills leverage Claude AI with extended reasoning to correlate MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance) with the vulnerability's attack chain. Practitioners would observe detection patterns flagging: (1) unauthenticated HTTP POST requests to booking endpoints lacking nonce tokens, indicating TA0001 exploitation attempts; (2) payloads containing script tags or event handlers in firstName/lastName parameters that bypass sanitize_text_field(); (3) stored XSS indicators where malicious input persists in the database and reflects in admin-facing booking detail pages. Casky's analysis would surface the critical gap between input sanitization and output encoding, helping security teams identify similar patterns across custom WordPress plugins and prioritize remediation before attackers weaponize this for privilege escalation or credential harvesting.

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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323 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-6286.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

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